Two weeks ago, we kicked off a set of blog posts focused on a series of articles from EDN/AspenCore on how the electronics industry has been responding to the pandemic. (These articles appeared in EE Times.) In my first post, I summarized an article by Majeed Ahmad that offered a “sneak peek into the brand-new design ecosystem built around the fight against the coronavirus pandemic.” Today, I’ll be covered several other pieces from the EDN series.
Hacking Bluetooth for COVID-19 contact tracing: With the virus spreading as rapidly as it has been, Asem Elshimi points out that “technology can shorten the delay between confirming an infected case and isolating all contacts,” noting that South Korea and Germany have effectively deployed digital contact tracing, while warning that tracing technology is promising but still maturing. He also warns that we don’t go overboard on how digital tracing – or any technology, for that matter – is a panacea. Digital tracing should, in fact, be used to supplement the more traditional approaches, not replace them.
That said, Bluetooth Low Energy (LE) is on an awful lot of smartphones, and the overwhelming majority of American adults own a smartphone. Every smartphone equipped with Bluetooth radio could be used to broadcast and receive encrypted messages from phones that are nearby. Records of all these contacts could be kept in the cloud. When someone is diagnosed with COVID-19, all their contacts can be notified and asked to quarantine. This solution is imperfect, and some Bluetooth features would need to be worked around. But the ubiquity of Bluetooth technology makes this approach worth pursuing.
Received signal strength indicator (RSSI) technology may offer the fastest path to rolling out Bluetooth-based contact tracking. There are downsides to it (including the possibility of too many false negatives and false positives), and the distance resolution is limited. Still, it holds promise. An alternative to RSSI is using Bluetooth direction-finding technologies, which would work better in those areas where RSSI is prone to false positives and false negatives. Unfortunately, most smartphones on the market are ready for RSSI, not for direction-finding technologies.
How about bracelets, rather than smartphones? In his next article on Bluetooth, Asam proposes the idea of Using privacy-centric Bluetooth bracelets for COVDI-19 contact tracing.
The alternative to smartphone solutions is wearable Bluetooth tags or bracelets. Bluetooth bracelets can be developed at a cost of $1 or $2 each, and they could operate for up to 10 years on a coin cell battery. Bluetooth bracelets can be manufactured using Bluetooth direction-finding technology as well as other more accurate Bluetooth location measurement technologies. This ready-for-deployment solution can be used to tackle densely populated urban environments where smartphone RSSI distance resolution is insufficient.
In the foreseeable future, highly-dense commercial environments, such as hospitals, offices, and retail spaces, could be populated with Bluetooth direction-finding gateways. People would be asked to wear Bluetooth bracelets to enter buildings and facilities. Every individual would actively check whether he or she is exposed to a confirmed case or not.
With any location tracking technology, privacy is always an issue. In this area, bracelets which, unlike smartphones, don’t need to know anything about who you are – they’re “identity-blind” – is a better solution.
In System design considerations for contact-tracing Bluetooth bracelets, Asam lists a number of things designers should keep in mind, including whether to use the bracelets for contact-tracing only, or to incorporate more sophisticated health-tracking technologies; just how the bracelet is going to be communicating with the Internet; and how the bracelets will be decommissioned once the COVID emergency is over. A final consideration: how to dispose of the bracelets once they’re no longer useful. We won’t want to let all the electronics turn into e-waste!
Hardware and software for building contact-tracing Bluetooth bracelets rounds out the mini-series on Bluetooth bracelets.
A wearable bracelet design consists of a Bluetooth SoC, an antenna, a coin-cell battery, and the software that enables it to do its work.
…While these are simple and well understood components, the choices you make in the initial design can have significant impact on time to market and cost. Semiconductor solution providers often offer design references for product designers. Utilizing design references can expedite the design process and achieve optimal performance of the SoC. Alternatively, semiconductor companies also offer system-in-package (SiP) modules that integrate all the needed components inside a package.
Asam includes a helpful table from Silicon Labs illustrating how different hardware components impact RF performance. He then discusses the importance of software, which may or may not be provided with the SoC, and the connectivity challenges that need to be addressed.
All in all, these articles offered an interesting look at a technology that may prove helpful to our getting on top of the COVID-19 pandemic.